Include a version number in the serialized JSON output

[dsherret]

We’re going to be changing the output of deno info --json in 2.0. To help with this change and future changes, we should include a version number in the JSON output so people using this output can quickly tell if they support it without having to version sniff the binary and know which version something changed or have to detect the shape.

Related: #228

This should only be done when releasing deno_graph with the new schema changes.

[dsherret]

This should actually only be bother to be done in the CLI because it extends the schema. Closing.